Direct digital synthesis (DDS) has been used to produce analog waveforms, such as a sine wave, of various frequencies and profiles. The ability to produce the waveforms accurately and to control the waveforms may be important for various applications and industries such as communications and electronic warfare. DDS devices generate a time-varying signal in digital form and then perform a digital-to-analog conversion. DDS devices generally provide fast switching between output frequencies, fine frequency resolution, and operation over a broad spectrum of frequencies.
A DDS device may generally include a phase accumulator, a phase-to-amplitude converter, and a digital-to-analog converter (DAC). The frequency of a DDS output generally depends on a reference clock frequency and a binary number input to the phase accumulator (referred to as a frequency control word). The phase accumulator computes phase values representing phase angles and the phase-to-amplitude converter outputs digital amplitude values corresponding to the phase values (e.g., a sine of the phase angle). The DAC converts the digital amplitude values into a corresponding analog amplitude (e.g., voltage or current), thereby producing an analog sinusoidal output signal.
Although conventional DDS devices provide accurate analog waveforms and allow the frequency to be changed, conventional DDS devices are associated with shortcomings.